Which of the following organ is not involved in calcium metabolism?

Calcium metabolism refers to the movements and regulation of calcium ions (Ca2+) in and out of various body compaments, such as the gastrointestinal tract, the blood plasma, the extracellular and intracellular fluids, and bone tissue. An impoant aspect of calcium metabolism is plasma calcium homeostasis, the regulation of calcium ions in the blood plasma within narrow limits. In this process, bone tissue acts as a calcium storage center for deposits and withdrawals as needed by the blood, continual bone remodeling.:276-277 Derangement of this mechanism leads to hypercalcemia or hypocalcemia, both of which can have consequences for health. The level of the calcium in humans' plasma is regulated by calcitonin and parathyroid hormone (PTH); calcitonin is released by the thyroid gland when its plasma level is above its set normal point (in order to lower calcium level); PTH is released by the parathyroid glands when calcium level falls below set point Ref: guyton and hall textbook of medical physiology 12 edition page number :577,578,579